1. Field of the Invention
The present invention relates to a high-intensity laser device which is suitable for use as a laser light source of an exposure apparatus for exposing an exposure surface at a photosensitive material or the like with a laser beam which is spatially modulated by a spatial light modulation device in accordance with image data.
2. Description of the Related Art
Heretofore, an exposure apparatus which employs a spatial light modulation device such as a digital micromirror device (DMD) or the like for carrying out image exposure with light beams modulated in accordance with image data has been proposed in Japanese Patent Application No. 2002-149888, which is a prior application which has not yet been published.
A DMD thereof is structured as, for example, a mirror device in which numerous micromirrors, which alter angles of reflection surfaces thereof in accordance with control signals, are arranged two-dimensionally on a semiconductor support of silicon or the like.
An exposure apparatus which utilizes such a DMD is structured such that, for example, a laser beam emitted from a laser beam-emitting laser light source is collimated at a lens system, is reflected at the DMD, which is disposed substantially at a focusing position of the lens system, passes through an aperture, and is focused onto an exposure surface by another lens system.
In such an exposure apparatus, control signals are generated in accordance with image data or the like. Each of the micromirrors of the DMD is controlled to ‘on’ or ‘off’ by an unillustrated control device, on the basis of the control signals, to modulate (deflect) the laser beam. A portion of (light flux of) the laser beam is blocked by passing the modulated laser beam through apertures, and spot diameters of the laser beam are controlled to have a predetermined size at the exposure surface. In addition, the beam spots are formed with a shape of the beam spots (a spot shape) being a predetermined shape, and the beam spots are irradiated onto the exposure surface for exposing the same.
In this exposure apparatus, a photosensitive material (a photoresist or the like) is provided at a recording surface. The beam spots which are formed and projected by the apertures are irradiated onto the photosensitive material from an exposure head of the exposure apparatus. While positions of these beam spots are relatively moved with respect to the photosensitive material, the DMD is adjusted in accordance with the data. Thus, a process of pattern-exposure on the photosensitive material can be implemented.
For laser light which is emitted from laser devices which are employed at light sources of such exposure apparatuses, higher output is sought. Accordingly, as a laser device which is capable of emitting high-power laser light, a multiplex laser light source with a plurality of semiconductor laser elements and one multi-mode optical fiber, in which laser beams emitted from the plurality of semiconductor laser devices ate multiplexed at the multi-mode optical fiber, has been proposed (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2002-202442).
To provide a laser output that is required in an exposure apparatus, it is necessary to bundle a plurality of these multiplex laser light sources for use, Further, in order to perform high-precision imaging, it is required that a light source portion has high intensity. However, when these multiplex laser light sources, which conventionally have employed commonly-used fibers with a cladding diameter of 125 μm, are bundled, intensity is reduced by an amount corresponding to cladding regions, which do not contribute to light propagation, and the intensity is inadequate for the required intensity.
In order to structure a high-precision exposure system in which resolution is improved, with a conventional exposure apparatus as described above, a laser device which emits high-intensity laser light with a high power that is necessary for functionality as a high-precision exposure apparatus is called for.